Skin cancer is one of the cancers that most aggravates the problem in public health. Among the types of cancer, melanoma is the most aggressive type. Its early diagnosis is essential to increase the possibility of adequate treatment, aiming to reduce the mortality rate. Dermatologists generally use manual methods to diagnose skin lesions. These methods, in addition to being time-consuming, as they are performed manually, can present different results for the same lesion when analyzed by different specialists. Therefore, an automated diagnosis may be necessary to deal with this issue as well as avoid invasive tests. For this, the task of segmenting the skin lesion in the dermoscopic image can be fundamental, as it is a basic task in the image analysis process. In the present work, a Convolutional Neural Network (CNN) model, based on the U-Net, is used to segment the lesion in dermoscopic images. This proposal achieved an accuracy of 0.949 and Jaccard of 0.833 for the 2017 ISIC base, and an accuracy of 0.954 and Jaccard of 0.850 for the 2018 ISIC base. The proposed model has a simpler architecture, in addition to requiring less computational resources. The experiments made it possible to observe that the proposed model results are promising compared with other CNN models presented in the literature.